US 2006/0142107 A1Published application

Hydraulic control apparatus

AssigneeToshiba Kikai Kabushiki Kaisha

InventorsMasayuki Kobayashi, Kazumichi Aoki

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Abstract

To provide a hydraulic control apparatus enabling to prevent failure due to occurrence of hunting, to elevate performance of a hydraulic control valve, and to improve operation efficiency through effectively conducting the bleed off. The hydraulic control apparatus is provided with a variable capacity pump 7, a first change over valve group A including at least one change over valve connected with a first delivery line 12A branched from a delivery line 12 of the variable capacity pump and arranged to have load sensing function, a second change over valve group B including at least one change over valve connected with a second delivery line 12B branched from the delivery line of the variable capacity pump, and an open and close motion valve 136 and a compensation valve 138 connected to the downstream of the open and close motion valve, which constitute a pressure compensation flow control means connected through the second delivery line and the second change over valve group. A hydraulic passage 148A is formed for bleeding off in the compensation valve, wherein the bleeding off is selectively conducted in accordance with a state of operation in the hydraulic circuit, in a way that in case of relatively small demand for the flow rate in the hydraulic circuit, such as the sole operation for revolution, the bleeding off is conducted so as to suppress the hunting, and in case that demand for the flow rate increases in the hydraulic circuit because of complexity operation combining the heavy load with the revolution operation, the bleeding off is not conducted.

A hydraulic control apparatus comprising:

a variable capacity pump,
a first change over valve group including at least one change over valve connected with a first delivery line branched from a delivery line of the variable capacity pump and arranged to have load sensing function,
a delivery flow control means for adjusting delivery flow rate of the variable capacity pump by receiving a hydraulic oil pressure signal from a load sensing line arranged in accordance with the change over valve having the load sensing function,
a second change over valve group including at least one change over valve connected with a second delivery line branched from the delivery line of the variable capacity pump,
an open and close motion valve connected with the second delivery line at a upstream side of the second change over valve group and having functions of open and close, and throttle in accordance with a hydraulic operation pressure signal to the change over valve belonging to the second change over valve group, and
a compensation valve arranged at a downstream side of the open and close motion valve an outlet side of the compensation valve being connected with the second change over valve group, wherein one side of the compensation valve is forced through force caused by hydraulic oil pressure at an outlet port of the open and close motion valve and a spring with a given spring force, and the opposite side of the compensation valve is forced through force caused by hydraulic oil pressure on the second delivery line, wherein the compensation valve is acted in the direction of opening by hydraulic oil pressure supplied from the outlet of the open and close motion valve due to the force of the one side, and is acted in the direction of closing by hydraulic oil pressure supplied from the inlet of the open and close motion valve due to the force of the opposite side, and
wherein said compensation valve is provided with a bleed off passage which is connected with the outlet side of the open and close motion valve, and hydraulically communicates with a tank side when the force of said one side is superior to the force of said opposite side.

4 more elements

Facts

Application

11/315,188Filed 23 Dec 2005

Priority

JP 2004-38181028 Dec 2004

Published

29 Jun 2006

Term ends

Not estimatedThe source records don’t support an estimate.

Classification16 codes

F15B 11/055
Specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive: by adjusting the pump output or bypass
F16H 61/40
Control of exclusively fluid gearing: hydrostatic
F16H 61/4017
Control of circuit pressure: control of high pressure, e.g. avoiding excess pressure by a relief valve
F16H 61/4061
Hydrostatic: control related to directional control valves, e.g. change-over valves, for crossing the feeding conduits

Abstract

Claims7